if (unfiltered instanceof FilteredMultiset) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.
      FilteredMultiset<E> filtered = (FilteredMultiset<E>) unfiltered;
      Predicate<E> combinedPredicate = Predicates.and(filtered.predicate, predicate);
      return new FilteredMultiset<>(filtered.unfiltered, combinedPredicate);
    }

    if (unfiltered instanceof FilteredMultiset) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.
      FilteredMultiset<E> filtered = (FilteredMultiset<E>) unfiltered;
      Predicate<E> combinedPredicate = Predicates.and(filtered.predicate, predicate);
      return new FilteredMultiset<>(filtered.unfiltered, combinedPredicate);
    }